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IVF with Next Generation Sequencing
A recent study compared the efficacy of two types of preimplantation genetic screening (PGS) used with IVF and single embryo transfer: next generation sequencing (NGS), and array Comparative Genomic Hybridization (aCGH). The researchers determined that clinical and ongoing pregnancy rates are comparable.
We spoke to Dr. John Zhang to learn more about the technologies. Zhang is one of the authors of the randomized clinical study, and is founder and medical director of New Hope Fertility Center in New York City.
FertilityAuthority: How are NGS and Array CGH different?
Dr. Zhang: Both aCGH and NGS are very similar in that they screen embryos for aneuploidy, the abnormal number of chromosomes – either a monosomy (missing a chromosome) or a trisomy (an extra chromosome). What makes NGS unique is its capability to detect mosaic embryos whereas aCGH cannot. Mosacism is when an embryo’s cells exhibit different genotypes. NGS determines if an embryo is mosaic and pinpoints which chromosome is affected.
Q: Based on the study results, can you recommend NGS over aCGH?
A: At New Hope Fertility Center, we have currently made the switch completely from aCGH to NGS. The reason for this change is to ensure we have all the information we can about the embryos prior to choosing one for implantation. Our hope is that in the near future, NGS will become a more affordable PGS. We always suggest patients seek out the most trusted and latest technologies. Often new doesn't mean better – they have to be trusted too. We are confident in recommending NGS.
Q: How does NGS affect your clinical practice?
A: The biggest thing that makes NGS difficult is what you do with embryos that are deemed mosaic. Do you simply dispose of them or do you transfer them in the hopes that a live birth will occur? These are all questions that are being asked within the field of IVF. No one really has the correct answer, so additional research will need to be conducted. In the end it might simply come down to a moral and ethical debate.